Digital images are becoming an increasingly popular form of infoimaging. One reason for this popularity is the ease with which users can manipulate, edit, alter and enhance such digital images. For example, users often use manual digital imaging and editing tools, such as the crop and zoom tools provided in the Kodak Picture CD software sold by Eastman Kodak Company, Rochester, N.Y., U.S.A., to improve the appearance of digital images. These image editing tools allow a user to limit the image content of an image to emphasize important elements in the image. This is known in the art as cropping an image. The cropped image incorporates less image data than the original image. It will be appreciated however, that a digital image, once captured, has a fixed amount of image data associated therewith. When such a digital image is cropped, some of this data is discarded.
Accordingly, when cropped and non-cropped images are rendered for example in a photographic print of the same image quality, the non-cropped images will appear to be larger than the cropped images. Many consumers find the appearance of such images unsatisfying and also elect to re-enlarge the selected portions of cropped images so that they have the appear to have been captured at an image size that is consistent with non-cropped images. Because this re-enlargement simulates what would have happened had the photographer zoomed her camera in toward the subject using a telephoto lens, most digital imaging algorithms provide an automatic “zoom and crop” function which allows a user to designate a selection area in a digital image and that automatically adjusts the selection area to match the area of a non-cropped image.
Accordingly, when the enlargement portion of the process occurs on an image with a reduced amount of data, the image that results from the zoom and crop processing has a reduced image resolution as compared to images that have not been subject to the same process. Where only small portions of the original image are cropped, this reduction in resolution is not always significant. However, as the cropping becomes more aggressive with greater amounts of data being discarded, the effective image resolution of the processed image can degrade noticeably. This effect can reduce consumer satisfaction with the zoom and crop processed image.
Often, zoom and crop functions are performed using image processing systems such as cameras, personal computers, kiosks, personal digital assistants, network centric systems, other devices. These devices commonly have a display for presenting a digital image and a user interface to permit a user to designate a selection area within an image for use in forming a zoom and crop processed image. The digital image data contained the selection area is processed using a zoom and crop algorithm to form a zoom and crop processed image and an evaluation image representing the zoom and crop processed image is formed for presentation on the display. Users often rely upon the appearance of the evaluation image as presented in the display in order to determine whether the zoom and crop processed image represented by the evaluation image has a preferred appearance. Where the evaluation image has an acceptable appearance, users will often elect to store the zoom and cropped processed image, or use a printer or like device to render the zoom and cropped processed image on a film fabric or paper.
However, the limited display resolution of conventional electronic displays and, in particular, small sized displays of the type commonly used in conjunction with digital cameras can mask the loss of resolution in a zoom and crop processed image. Accordingly, users can designate a selection area that comprises only a fraction of the original image without realizing that such aggressive use of the zoom and crop algorithm can reach a point where so much of the data comprising the originally captured digital image has been discarded that the zoom and crop processed image does not have a minimum amount of data necessary to permit the zoom and crop processed image to have a preferred appearance when presented on a high resolution display or rendered by printers or other image forming devices that have relatively high levels of image resolution.
In some cases, this problem can be addressed by the use of image processing algorithms that the attempt to increase the effective resolution him of a low resolution images him by interpolating data from the low resolution image to create a high resolution image. One example of such an algorithm can be found in U.S. Pat. No. 6,058,248 entitled “Computerized Method for Improving Data Resolution” filed by Atkins et al. on May 25, 1999. However, it will be appreciated that such interpolation techniques can introduce unanticipated artifacts in an image which themselves can reduce the acceptability of the image.
Some image processing algorithms, printers, kiosks, and commercial image rendering establishments examine each digital image submitted for high resolution display or rendering to determine whether the image has adequate image resolution to permit a print formed therefrom to have a preferred appearance. For example, OFOTO, Inc. of Emeryville, Calif., is an online photography service that provides top-quality silver halide prints for digital and film camera users. Ofoto's Web site, www.ofoto.com, gives photographers a new and easier way to store and share digital images on line. Once online, these images can be easily edited, cropped, or enhanced with borders and special effects, by using Ofoto's free online tools. Ofoto provides a print image resolution warning when a user submits a digital image for printing that does not meet minimum resolution requirements for a selected type of printed output. While the approach of providing such a warning usefully alerts users that an image submitted for printing does not have sufficient image resolution, it is not always convenient for the user to adjust the image at the time that the warning is received.
Alternatively, zoom and crop image editing algorithms are known that require a user to designate a size that they anticipate that a rendered output image will have and that provide predefined selection area templates that a user can move about an image in order to make a selection area designation. For example, commonly assigned U.S. Pat. No. 5,619,738 entitled “Pre-Processing Image Editing” filed by Petruchick et al. on Apr. 8, 1997 describes a film camera including an electronic display and a driver for presenting movable markers to frame and edit an electronically displayed image. Electronic manipulation of the markers provides for zooming and cropping the image as well as changing the image formation and horizontal and vertical orientation. The camera includes an input for selecting a print format from a predetermine set of print formats each having a predetermined size and aspect ratio. Once that a print format is selected, having a predetermined aspect ratio, cropping is limited to selections that are consistent with that aspect ratio and the standard widths for photographic paper. Further, after a print size and aspect ratio selection is made, markers are formed in the display of the digital image that conform to the size and aspect ratio selected. These markers can be maneuvered within the evaluation image to designate the selected area.
Commonly assigned U.S. Pat. No. 6,018,397, entitled “Digital Image Processing With Indication to User of Hardcopy Output Image Quality” filed by Cloutier et al. on Feb. 13, 1998 describes a digital image processor that establishes a boundary level of acceptable hardcopy print quality level based on selected image print size and printing magnification and provides a warning to a user prior to generation of the hardcopy print that alerts the user when the determine print image quality will be unsatisfactory. This system receives inputs including digital image data representative of an image to be reproduced in hardcopy at a user-selected size, hardcopy image quality information being representative of acceptable and unacceptable levels of hardcopy image quality produced with said hardcopy image reproduction and information representative of the desired magnification and user selected size of the hardcopy image to be output and indicates whether this combination will generate images having an acceptable appearance. The '397 patent provides a warning to a user when the user selects a combination that may not yield acceptable results prior to submitting the image for hard copy image formation. While useful and commercially valuable, this approach requires a user to designate a selection area within the image and indicate a desired output before providing the warning.
However, there viable approaches are needed for helping a user to make selection area designations for zoom and crop processing of an image, without requiring the user to decide in advance what hardcopy outputs or other forms of output use that the user may make of the image. In particular, what is needed is an image processing algorithm that allows a user to make flexible selection area designations for use in zoom and crop processing and yet provides real-time feedback from which a user can appreciate the potential impact of such selections on the use of a zoom and crop processed image based upon a selected area.